Distribution of full motion video data has evolved from early television broadcasting and cable distribution networks to direct broadcast satellite television. Recently, several different wideband digital distribution networks have been proposed for offering subscribers an array of video services, including true Video On Demand service. The following U.S. Patents disclose representative examples of such digital video distributions networks: U.S. Pat. No. 5,253,275 to Yurt et al., U.S. Pat. No. 5,132,992 to Yurt et al., U.S. Pat. No. 5,133,079 to Ballantyne et al., U.S. Pat. No. 5,130,792 to Tindell et al., U.S. Pat. No. 5,057,932 to Lang, U.S. Pat. No. 4,963,995 to Lang, U.S. Pat. No. 4,949,187 to Cohen, and U.S. Pat. No. 4,506,387 to Walter.
For example, Litteral et al. U.S. Pat. No. 5,247,347 discloses a digital video distribution network providing subscribers with access to multiple Video On Demand service providers through the public switched telephone network. Systems such as described by Litteral et al., however, are limited. The Litteral et al. system for example relies on digital cross connect switching to multiplexers which supply a single broadband channel to a subscriber's premises via the subscriber's twisted wire pair telephone line. The resulting single channel, point-to-point transmissions are effective for interactive type services, but cannot provide viewers with the array of broadcast services now widely available through community antenna type cable television systems commonly known as CATV systems.
An emerging packet switching technology, referred to as asynchronous transfer mode (ATM) switching provides the high speed and flexibility to transport large quantities of information to large numbers of subscribers, in either point-to-point configurations or point-to-multipoint configurations (see e.g. U.S. Pat. No. 5,345,558 to Opher et al). ATM networks communicate all information in cells which comprise a well-defined and size-limited header area and a user information or payload area. Transfer is asynchronous in the sense that the recurrence of cells that contain information from any particular sender is not necessarily periodic. Each sending device using the ATM network submits a cell for transfer when they have a cell to send, not when they have an assigned or available transmission time slot.
The standardized ATM cell format includes a 5-byte header field and a 48-byte information or payload field. The information field is available to the user to transport payload data. The standard defines the header field as carrying information pertaining to ATM functionality, including information for identification of the cells for routing purposes. In particular, the header includes a virtual path identifier (VPI) and a virtual channel identifier (VCI).
An ATM switch comprises a number of switching elements which act together to transport a cell from the input of the switch to the correct output. In the prior art ATM networks, an ATM switch performs two primary tasks: the transport of cells from the input port to the correct output port and translation of VPI/VCI information. In the prior art ATM networks, translation of the VPI/VCI by each switch is important because in such ATM networks the contents of these fields only have local meaning. The same VPI/VCI data is interpreted differently by each switch. Thus, each switch providing transport of cells for a particular communication session translates the VPI/VCI information in the cells relating to that session prior to supplying the cell to an output of the switch.
A number of patents have now suggested transport of video, including broadcast video, using ATM. U.S. Pat. No. 5,260,783 to Dixit discloses a specific technique for digitizing video based on the detected degree of motion and transport of the encoded video information in ATM cell form. U.S. Pat. No. 5,027,400 to Baji et al. discloses a multimedia broadcast system utilizing ATM from the broadcast station all the way to the subscriber terminal. U.S. Pat. No. 5,228,028 to Cucchi discloses a technique for organizing encoded video information to minimize cell loss during ATM transport. The Opher et al. Patent cited above discloses a specific manipulation of the VPI and VCI fields of ATM cells to distinguish cells carrying broadcast information from other cells.
More recently, the assignee of the present application has proposed a number of network architectures for offering a full range of broadcast video, interactive video, narrowband data and voice telephone services. The proposed networks all rely at least in part of ATM transport. Exemplary disclosures of two such networks may be found in copending U.S. patent application Ser. No. 08/304,174, filed Sep. 12, 1994, entitled Level 1 Gateway for Video Dial Tone Networks (attorney docket no. 680-093), the disclosure of which regarding those ATM networks is incorporated herein in its entirety by reference.
To place such video distribution networks using ATM into actual service, a need exists for an efficient manner to manage the network services. For a variety of reasons, a network operating company must be able to determine, monitor and track what programs information service providers put on various ATM channels through the network and how the program cells pass through the network. It may also be useful to track what programs, transported in ATM cell form, a subscriber actually receives and views. To the extent that earlier systems have attempted to monitor network traffic, there has been no use of any of the header information in the ATM cells themselves. Possibly because ATM components translated VPI/VCI values as cells passed therethrough, the VPI/VCI values have not been used to administer network operation.